Construction method of large-diameter concrete filled steel tube variable-diameter pile foundation

Abstract

The invention relates to a construction method for a large-diameter concrete-filled steel tube variable-diameter pile foundation, which comprises the following steps of: sequentially performing equal-diameter drilling on an upper pile hole, and heightening a steel tube pile after the upper pile hole is drilled by a set depth; the middle pile hole is located in the bottom of the upper pile hole and located in the rock stratum, and the drilling machine conducts graded hole expanding drilling from inside to outside through a drilling bucket with the diameter increasing in sequence; the lower pile hole is subjected to blasting and slag removal, the lower pile hole is located in the bottom of the middle pile hole and located in the bed rock, a plurality of blasting holes are drilled downwards in the hole bottom of the middle pile hole, explosives are buried in the blasting holes, loose blasting is conducted, and a drilling machine drills holes and removes slag till the set hole depth is reached. According to the construction method, according to the geological condition that the upper portion of the pile hole is soft and the lower portion of the pile hole is hard, upper pile hole equal-diameter drilling, middle pile hole chambering drilling and lower pile hole blasting are sequentially adopted for step-by-step drilling construction, the utilization rate of a drilling machine is increased, the hole forming efficiency of the pile hole is improved, and the pile foundation construction cost is reduced.

Description

technical field [0001] The present application relates to the technical field of bridge foundation construction, in particular to a construction method for a large-diameter concrete-filled steel tube variable-diameter pile foundation. Background technique [0002] With the continuous development of railways, highways and urban high-rise buildings, due to the continuous improvement of the bearing capacity of pile foundations, the diameter and depth of pile foundations are becoming larger and larger. to weathered rock formations. Large-diameter rock-socketed bored piles have become the preferred type of foundation engineering and are increasingly used in production. How to ensure the engineering quality and schedule of large-diameter rock-socketed bored piles and control costs during construction has become a problem that must be faced in the construction of large-diameter rock-socketed bored piles. [0003] During the construction of bored piles, the rotary drilling rig has...

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Problems solved by technology

[0005] The embodiment of the present application provides a construction method for large-diameter concrete-filled steel pipe variable-diameter pile foundations to solve the problem of the low drilling speed of the rotary drilling rig in the related art after entering the hard rock formation, which leads to a significant increase in the construction cost of the rotary drilling rig in the rock entry stage. The problem

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